VDSL SNR Upload max possible?

[#1]

Hi

New to Plusnet having been on BT's Fibre 1 product for last 4 years.

Over the time with BT I've seen the availability checker show increasingly faster numbers for both Down and Upload speeds on both Clean and Impacted categories.

Type	2020	2021	2022	2023	2024	2025 (May)
Clean Download High	54.1	53	56.3	53.7	69.7	71.9
Clean Download Low	35	35	40	39.1	49	49
Clean Upload High	11	10.3	11.3	10	17	17.7
Clean Upload Low	7.2	7	7.5	7	10.7	11.3
Clean Handback	32.4	32.4	35	35	42.5	44
Impacted Download High	52.7	51.4	54.9	52.4	68	70.3
Impacted Download Low	32.4	32.9	35	35	42.8	44
Impacted Upload High	10.9	10	11.1	10	16.9	17.5
Impacted Upload Low	6.8	6.5	7	6.5	9.6	10
Impacted Handback	27.4	27.4	30	27.4	35	35

Whilst the availability tracker numbers have increased over the last 4 years, my sync speeds (either with the BT hubs, a HG612 Modem and now the Plusnet Hub Two) have been pretty consistent at 48 down (at between 3.5 and 3 SNR) and 9.5 up (at between 6 and 6.5 SNR).

I'd always assumed that with BT my speed was being capped out as I was on their 48/10 product, but I believe Plusnet's Fibre 74 is using a 80/20 product, so expected the upload speeds to improve a little.  Does Upload SNR also train down to a 3 SNR profile, or is it capped out at a higher rate?

Cheers

[#2]

but I believe Plusnet's Fibre 74 is using a 80/20 product,

Not neccesarily. Plusnet will normally provision on an 80/20 profile BUT if the Downstream speed estimate is not much better than 40 , they will likely provision on a 40/10 profile for better stability

[#3]

Ah ok - how would I check which profile they've provisioned?  I'd have presumed as they were advising on the sign-up page estimated downloads between 44-65Mb and uploads between 10-16Mb with a minimum guarantee of 40Mb they would also apply a profile which would be capable of that range?

Cheers
Matt

[#4 · Accepted solution]

There's no actual way to see what profile the line is provisioned on. However it can be deduced from the line stats

Having re-read you original post

a HG612 Modem and now the Plusnet Hub Two) have been pretty consistent at 48 down (at between 3.5 and 3 SNR) and 9.5 up (at between 6 and 6.5 SNR).

With a downstream sync of 48, my guess is that with BT you were on a 55/10 profile and either the profile hasn't changed on the move to PLusnet (although PN dont do a 55/10 product ) or you've been changed to an 80/20.

Unless there's a fault on the line ( and since you're above the DS handback Openreach wont accept a fault ) you won't get any improvement. The upstream sync is limited by the 6db noise margin, I dont believe it will reduce to a 3db target (unlike the DS)

[#5]

Ah ok - was just about to edit my post to say I was getting over the 40Mb as well!

Makes sense if upload is limited to an SNR of 6db as well.  Looks like the Wholesale Checker is being rather optimistic in it's estimates (pretty certain my house hasn't moved over the last 4 years, neither has the cabinet!).

Thanks for coming back to me so quickly @MisterW  👍

[#6]

The problem with the checker is that it assumes a good quality copper line and estimates speed by line length. If there is any aluminium in there the speeds will be well down. The fact that your ds target margin is at 3db means the DLM thinks its relatively error free (otherwise it would have stuck at 6db).